Spain was one of the hardest-hit countries when the coronavirus struck Europe this year before a strict lockdown helped reduce the outbreak's spread.

But infections have surged since the lockdown measures were fully removed at the end of June, especially in Madrid, with the rise in infections often linked to the return of nightlife and social gatherings.

"We are worried about the state of public health and the evolution of the virus in Madrid," Sanchez said in an interview with news radio Ser.

The socialist premier added that "some" regional governments which he did not identify needed to boost their ability to track Covid-19 cases and improve their "strategic capacities" in the fight against the virus.

Spain's central government last week made 2,000 soldiers available to help regional governments, which are responsible for health care, to track people who have been exposed to those infected with virus.

So far 11 of the country's 17 regional governments had requested soldiers, Sanchez said. 

Madrid, which is governed by the conservative Popular Party, requested 150 soldiers.

Spain registered over 23,000 new Covid-19 cases since Friday, health emergency chief Fernando Simon told a news conference on Monday, bringing the total to 462,858.

Of the 1,656 hospitalizations from the disease during the last seven days, 420, or 25 percent, were in Madrid, according to health ministry figures.

The region accounted for nearly half of the 141 deaths in the last seven days.

Spain has recorded a total of 29,094 virus deaths since the start of the pandemic, one of the world's highest tolls.